[Epidemiological characteristics of infectious diseases in Croatian island isolates]

In isolated human communities infectious diseases often occur in unusual forms and reveal unexpected patterns of spread. This is not due to differences in biological characteristics of affected populations or infectious agents, but rather a consequence of specific changes in conditions under which the epidemics occur in isolated populations. The aim of this study was to analyze the patterns of the occurrence of salmonellosis, streptococcal angina, varicellae and scabies in 10 Croatian islands (Krk, Cres, Losinj, Rab, Pag, Brac, Hvar, Korcula, Vis and Lastovo) and in the entire Croatian population between 1989 and 1998. The four investigated diseases were selected based on: (1) sufficient number of cases each year the islands to warrant appropriate analysis of occurrence patterns; (2) different pathogenic mechanisms which include alimentary and respiratory bacterial infection, highly contagious viral infection and parasitic disease. The comparison of standardized rates of infection between the island populations and Croatian general population revealed large differences. In the islands the epidemics were less frequent in time, but of much greater intensity, especially in smaller and very isolated communities. Factors such as specific food and water supply, ecologic peculiarities, sociodemographic structure and population subdivision could have contributed to the determination of epidemic patterns in human isolates.